1. Field of the Invention
The present invention relates to a photo mask with a development rate measuring pattern for measuring development rates at different areas of a wafer after forming a photo mask pattern using photolithography for the fabrication of a semiconductor device and a method for measuring the development rate uniformity using the photo mask.
2. Description of the Prior Art
As a wafer used for fabrication of semiconductor devices becomes larger than the general size of 4 inches, for example, 5 inches, 6 inches or 8 inches, the uniformity in development rate of a photo mask pattern at all areas of the wafer, may be greatly affected where the photo mask pattern is formed using a photolithography process involving three steps: a coating and alignment of a photoresist film, an exposure and a development. In the case of the 8-inch wafer, in particular, the uniform development rate is an important factor for achieving a high integration of semiconductor devices.
For this reason, a measurement of development rate at each area of a wafer is made. For example, the development rate uniformity can be checked by measuring development rates of predetermined patterns formed on corresponding areas of the wafer by use of critical dimension measuring equipment after carrying out the general photolithography process. However, such a conventional method requires a lot of time and the use of an expensive scanning electron microscope (SEM) as the critical dimension measuring equipment.